Wouldnt the red flag you mentioned allow you some advantage, even if its a bluff? The opponent might wonder what infact do you have in your hand that merits losing 2 cards rather than just 1, thus potentially causing them to slip up? Is this out of context when it comes to vintage?
It depends. Yes, in Type 1, just as in any card game, bluffing and psyching out an opponent have their place. However, if you really have nothing in hand, you are probably not going to want to pitch a blue card first turn if you have no genuine reason to do so. I can think of several reasons why you wouldn't do this. First, duping your opponent into thinking your protecting something isn't going to have much effect on the first turn when after Duressing you, he is most likely to either pass the turn or kill you on the spot. Secondly, if you FoW a Duress, he might be tempted to FoW or Misdirect your FoW and then you're starting the game with 5 cards in hand (after your draw) and nothing on the table. Let's assume you're playing Meandeck Gifts (a very popular T1 deck) and you Force a Duress and he Forces it back at you. Your starting hand will have gone from: Force of Will, Polluted Delta, Mana Vault, Brainstorm, Gifts Ungiven, Mox Jet, and Island to:
Polluted Delta, Mana Vault, Mox Jet, Island.
Whatever psychological advantage you may have attempted to acquire simply wasn't worth the price paid.
You have a slim chance of topdecking something amazing, but otherwise you're probably going to lose.
That said, bluffing in T1 usually involves representing a counterspell that you don't have, not a killer spell. If I had a bomb in hand, I usually would want my opponent unprepared for it. Hey, Goblin Welder... meet Oath of Druids.

-BPK